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BioRxiv : the Preprint Server For... Apr 2024Lysosomes and related precursor organelles robustly build up in swollen axons that surround amyloid plaques and disrupted axonal lysosome transport has been implicated...
Lysosomes and related precursor organelles robustly build up in swollen axons that surround amyloid plaques and disrupted axonal lysosome transport has been implicated in worsening Alzheimer's pathology. Our prior studies have revealed that loss of Adaptor protein-4 (AP-4) complex function, linked primarily to Spastic Paraplegia (HSP), leads to a similar build of lysosomes in structures we term "AP-4 dystrophies". Surprisingly, these AP-4 dystrophies were also characterized by enrichment of components of APP processing machinery, β-site cleaving enzyme 1 (BACE1) and Presenilin 2. Our studies examining whether the abnormal axonal lysosome build up resulting from AP-4 loss could lead to amyloidogenesis revealed that the loss of AP-4 complex function in an Alzheimer's disease model resulted in a strong increase in size and abundance of amyloid plaques in the hippocampus and corpus callosum as well as increased microglial association with the plaques. Interestingly, we found a further increase in enrichment of the secretase, BACE1, in the axonal swellings of the plaques of Alzheimer model mice lacking AP-4 complex compared to those having normal AP-4 complex function, suggestive of increased amyloidogenic processing under this condition. Additionally, the exacerbation of plaque pathology was region-specific as it did not increase in the cortex. The burden of the AP-4 linked axonal dystrophies/AP-4 dystrophies was higher in the corpus callosum and hippocampus compared to the cortex, establishing the critical role of AP-4 -dependent axonal lysosome transport and maturation in regulating amyloidogenic amyloid precursor protein processing.
PubMed: 38617351
DOI: 10.1101/2024.03.31.587499 -
Biomedicine & Pharmacotherapy =... May 2024Total ginsenosides (TG), the major active constituents of ginseng, have been proven to be beneficial in treatment of Alzheimer's disease (AD). However, the underlying...
INTRODUCTION
Total ginsenosides (TG), the major active constituents of ginseng, have been proven to be beneficial in treatment of Alzheimer's disease (AD). However, the underlying mechanism of TG remains unclear.
METHODS
APP/PS1 mice and N2a/APP695 cells were used as in vivo and in vitro model, respectively. Morris water maze (MWM) was used to investigate behavioral changes of mice; neuronal pathological changes were assessed by hematoxylin and eosin (H&E) and nissl staining; immunofluorescence staining was used to examine amyloid beta (Aβ) deposition; Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to examine the expression of relative amyloidogenic genes and proteins. Moreover, the antagonist of PPARγ, GW9662, was used to determine whether the effects of TG on Aβ production were associated with PPARγ activity.
RESULTS
TG treatment increased the spatial learning and memory abilities of APP/PS1 mice while decreasing the Aβ accumulation in the cortex and hippocampus. In N2a/APP695 cells, TG treatment attenuated the secretion of Aβ1-40 and Aβ1-42 acting as an PPARγ agonist by inhibiting the translocation of NF-κB p65. Additionally, TG treatment also decreased the expression of amyloidogenic pathway related gene BACE1, PS1 and PS2.
CONCLUSIONS
TG treatment reduced the production of Aβ both in vivo and in vitro. Activating PPARγ might be a potential therapeutic target of TG in facilitating Aβ clearance and ameliorating cognitive deficiency in APP/PS1 mice.
Topics: Animals; Mice; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloid Precursor Protein Secretases; Cell Line, Tumor; Disease Models, Animal; Ginsenosides; Hippocampus; Maze Learning; Memory; Mice, Inbred C57BL; Mice, Transgenic; Peptide Fragments; PPAR gamma; Presenilin-1
PubMed: 38593704
DOI: 10.1016/j.biopha.2024.116577 -
Alzheimer's & Dementia : the Journal of... May 2024Fundamental questions remain about the key mechanisms that initiate Alzheimer's disease (AD) and the factors that promote its progression. Here we report the successful...
INTRODUCTION
Fundamental questions remain about the key mechanisms that initiate Alzheimer's disease (AD) and the factors that promote its progression. Here we report the successful generation of the first genetically engineered marmosets that carry knock-in (KI) point mutations in the presenilin 1 (PSEN1) gene that can be studied from birth throughout lifespan.
METHODS
CRISPR/Cas9 was used to generate marmosets with C410Y or A426P point mutations in PSEN1. Founders and their germline offspring are comprehensively studied longitudinally using non-invasive measures including behavior, biomarkers, neuroimaging, and multiomics signatures.
RESULTS
Prior to adulthood, increases in plasma amyloid beta were observed in PSEN1 mutation carriers relative to non-carriers. Analysis of brain revealed alterations in several enzyme-substrate interactions within the gamma secretase complex prior to adulthood.
DISCUSSION
Marmosets carrying KI point mutations in PSEN1 provide the opportunity to study the earliest primate-specific mechanisms that contribute to the molecular and cellular root causes of AD onset and progression.
HIGHLIGHTS
We report the successful generation of genetically engineered marmosets harboring knock-in point mutations in the PSEN1 gene. PSEN1 marmosets and their germline offspring recapitulate the early emergence of AD-related biomarkers. Studies as early in life as possible in PSEN1 marmosets will enable the identification of primate-specific mechanisms that drive disease progression.
Topics: Animals; Presenilin-1; Alzheimer Disease; Callithrix; Male; Female; Brain; Amyloid beta-Peptides; Disease Models, Animal; Point Mutation; Animals, Genetically Modified; CRISPR-Cas Systems; Gene Knock-In Techniques; Mutation; Humans
PubMed: 38574388
DOI: 10.1002/alz.13806 -
Frontiers in Molecular Neuroscience 2024A patient with the E280A mutation and homozygous for Christchurch () displayed extreme resistance to Alzheimer's disease (AD) cognitive decline and tauopathy, despite...
A patient with the E280A mutation and homozygous for Christchurch () displayed extreme resistance to Alzheimer's disease (AD) cognitive decline and tauopathy, despite having a high amyloid burden. To further investigate the differences in biological processes attributed to , we generated induced pluripotent stem (iPS) cell-derived cerebral organoids from this resistant case and a non-protected control, using CRISPR/Cas9 gene editing to modulate expression. In the cerebral organoids, we observed a protective pattern from early tau phosphorylation. ScRNA sequencing revealed regulation of Cadherin and Wnt signaling pathways by , with immunostaining indicating elevated β-catenin protein levels. Further reporter assays unexpectedly demonstrated that ApoE3Ch functions as a Wnt3a signaling enhancer. This work uncovered a neomorphic molecular mechanism of protection of ApoE3 Christchurch, which may serve as the foundation for the future development of protected case-inspired therapeutics targeting AD and tauopathies.
PubMed: 38571814
DOI: 10.3389/fnmol.2024.1373568 -
Stem Cell Research Jun 2024Presenilin-2 (PSEN2) mutation is one of the pathogenic factors of autosomal dominant early-onset Alzheimer's disease (EOAD). We generated a human induced pluripotent...
Presenilin-2 (PSEN2) mutation is one of the pathogenic factors of autosomal dominant early-onset Alzheimer's disease (EOAD). We generated a human induced pluripotent stem cell (iPSC) line from fibroblasts of an EOAD patient carrying PSEN2 mutation (c.716 T > C) utilizing Sendai reprogramming kit. The resulting iPSC line carried patient-specific point mutation, exhibited typical iPSC morphology, retained a normal karyotype, expressed pluripotency markers, and could form embryoid bodies. Established iPSC line serve as valuable resource for EOAD disease pathogenesis modelling and drug screening.
Topics: Humans; Induced Pluripotent Stem Cells; Fibroblasts; Presenilin-2; Mutation; Skin; Cell Line; Alzheimer Disease; Cell Differentiation; Cellular Reprogramming; Male
PubMed: 38531230
DOI: 10.1016/j.scr.2024.103391 -
ELife Mar 2024For over a century, brain research narrative has mainly centered on neuron cells. Accordingly, most neurodegenerative studies focus on neuronal dysfunction and their...
For over a century, brain research narrative has mainly centered on neuron cells. Accordingly, most neurodegenerative studies focus on neuronal dysfunction and their selective vulnerability, while we lack comprehensive analyses of other major cell types' contribution. By unifying spatial gene expression, structural MRI, and cell deconvolution, here we describe how the human brain distribution of canonical cell types extensively predicts tissue damage in 13 neurodegenerative conditions, including early- and late-onset Alzheimer's disease, Parkinson's disease, dementia with Lewy bodies, amyotrophic lateral sclerosis, mutations in presenilin-1, and 3 clinical variants of frontotemporal lobar degeneration (behavioral variant, semantic and non-fluent primary progressive aphasia) along with associated three-repeat and four-repeat tauopathies and TDP43 proteinopathies types A and C. We reconstructed comprehensive whole-brain reference maps of cellular abundance for six major cell types and identified characteristic axes of spatial overlapping with atrophy. Our results support the strong mediating role of non-neuronal cells, primarily microglia and astrocytes, in spatial vulnerability to tissue loss in neurodegeneration, with distinct and shared across-disorder pathomechanisms. These observations provide critical insights into the multicellular pathophysiology underlying spatiotemporal advance in neurodegeneration. Notably, they also emphasize the need to exceed the current neuro-centric view of brain diseases, supporting the imperative for cell-specific therapeutic targets in neurodegeneration.
Topics: Humans; Brain; Neurodegenerative Diseases; Neurons; Parkinson Disease; Brain Mapping
PubMed: 38512130
DOI: 10.7554/eLife.89368 -
Cell Death & Disease Mar 2024Craniofacial malformations, often associated with syndromes, are prevalent birth defects. Emerging evidence underscores the importance of mA modifications in various...
Craniofacial malformations, often associated with syndromes, are prevalent birth defects. Emerging evidence underscores the importance of mA modifications in various bioprocesses such as stem cell differentiation, tissue development, and tumorigenesis. Here, in vivo, experiments with zebrafish models revealed that mettl3-knockdown embryos at 144 h postfertilization exhibited aberrant craniofacial features, including altered mouth opening, jaw dimensions, ethmoid plate, tooth formation and hypoactive behavior. Similarly, low METTL3 expression inhibited the proliferation and migration of BMSCs, HEPM cells, and DPSCs. Loss of METTL3 led to reduced mRNA mA methylation and PSEN1 expression, impacting craniofacial phenotypes. Co-injection of mettl3 or psen1 mRNA rescued the level of Sox10 fusion protein, promoted voluntary movement, and mitigated abnormal craniofacial phenotypes induced by mettl3 knockdown in zebrafish. Mechanistically, YTHDF1 enhanced the mRNA stability of mA-modified PSEN1, while decreased METTL3-mediated mA methylation hindered β-catenin binding to PSEN1, suppressing Wnt/β-catenin signaling. Pharmacological activation of the Wnt/β-catenin pathway partially alleviated the phenotypes of mettl3 morphant and reversed the decreases in cell proliferation and migration induced by METTL3 silencing. This study elucidates the pivotal role of METTL3 in craniofacial development via the METTL3/YTHDF1/PSEN1/β-catenin signaling axis.
Topics: Animals; beta Catenin; Methylation; Methyltransferases; RNA, Messenger; Wnt Signaling Pathway; Zebrafish; Presenilin-1; Zebrafish Proteins
PubMed: 38509077
DOI: 10.1038/s41419-024-06606-9 -
Journal of Traditional Chinese Medicine... Apr 2024To discuss the influence of Sailuotong (, SLT) on the Neurovascular Unit (NVUs) of amyloid precursor protein (APP)/presenilin-1(PS1) mice and evaluate the role of gas...
OBJECTIVE
To discuss the influence of Sailuotong (, SLT) on the Neurovascular Unit (NVUs) of amyloid precursor protein (APP)/presenilin-1(PS1) mice and evaluate the role of gas supplementation in activating blood circulation during the progression of Alzheimer's disease (AD).
METHODS
The mice were allocated into the following nine groups: (a) the C57 Black (C57BL) sham-operated group (control group), (b) ischaemic treatment in C57BL mice (the C57 ischaemic group), (c) the APP/PS1 sham surgery group (APP/PS1 model group), (d) ischaemic treatment in APP/PS1 mice (APP/PS1 ischaemic group), (e) C57BL mice treated with aspirin following ischaemic treatment (C57BL ischaemic + aspirin group), (f) C57BL mice treated with SLT following ischaemic treatment (C57BL ischaemic + SLT group), (g) APP/PS1 mice treated with SLT (APP/PS1 + SLT group), (h) APP/PS1 mice treated with donepezil hydrochloride following ischaemic treatment (APP/PS1 ischaemic + donepezil hydrochloride group) and (i) APP/PS1 mice treated with SLT following ischaemic treatment (APP/PS1 ischaemic + SLT group). The ischaemic model was established by operating on the bilateral common carotid arteries and creating a microembolism. The Morris water maze and step-down tests were used to detect the spatial behaviour and memory ability of mice. The hippocampus of each mouse was observed by haematoxylin and eosin (HE) and Congo red staining. The ultrastructure of NVUs in each group was observed by electron microscopy, and various biochemical indicators were detected by enzyme-linked immunosorbent assay (ELISA). The protein expression level was detected by Western blot. The mRNA expression was detected by quantitative real-time polymerase chain reaction (qRT-PCR).
RESULTS
The results of the Morris water maze and step-down tests showed that ischemia reduced learning and memory in the mice, which were restored by SLT. The results of HE staining showed that SLT restored the pathological changes of the NVUs. The Congo red staining results revealed that SLT also improved the scattered orange-red sediments in the upper cortex and hippocampus of the APP/PS1 and APP/PS1 ischaemic mice. Furthermore, SLT significantly reduced the content of Aβ, improved the vascular endothelium and repaired the mitochondrial structures. The ELISA detection, western blot detection and qRT-PCR showed that SLT significantly increased the vascular endothelial growth factor (VEGF), angiopoietin and basic fibroblast growth factor, as well as the levels of gene and protein expression of low-density lipoprotein receptor-related protein-1 (LRP-1) and VEGF in brain tissue.
CONCLUSIONS
By increasing the expression of VEGF, SLT can promote vascular proliferation, up-regulate the expression of LRP-1, promote the clearance of Aβ and improve the cognitive impairment of APP/PS1 mice. These results confirm that SLT can improve AD by promoting vascular proliferation and Aβ clearance to protect the function of NVUs.
Topics: Mice; Animals; Amyloid beta-Protein Precursor; Alzheimer Disease; Mice, Transgenic; Vascular Endothelial Growth Factor A; Donepezil; Amyloid beta-Peptides; Presenilin-1; Congo Red; Mice, Inbred C57BL; Aspirin; Disease Models, Animal; Drugs, Chinese Herbal
PubMed: 38504535
DOI: 10.19852/j.cnki.jtcm.20240203.007 -
The Journal of Biological Chemistry Apr 2024The recently discovered interaction between Presenilin 1 (PS1), a catalytic subunit of γ-secretase responsible for generating amyloid-β peptides, and GLT-1, a major...
The recently discovered interaction between Presenilin 1 (PS1), a catalytic subunit of γ-secretase responsible for generating amyloid-β peptides, and GLT-1, a major glutamate transporter in the brain (EAAT2), provides a mechanistic link between these two key factors involved in Alzheimer's disease (AD) pathology. Modulating this interaction can be crucial to understand the consequence of such crosstalk in AD context and beyond. However, the interaction sites between these two proteins are unknown. Herein, we utilized an alanine scanning approach coupled with FRET-based fluorescence lifetime imaging microscopy to identify the interaction sites between PS1 and GLT-1 in their native environment within intact cells. We found that GLT-1 residues at position 276 to 279 (TM5) and PS1 residues at position 249 to 252 (TM6) are crucial for GLT-1-PS1 interaction. These results have been cross validated using AlphaFold Multimer prediction. To further investigate whether this interaction of endogenously expressed GLT-1 and PS1 can be prevented in primary neurons, we designed PS1/GLT-1 cell-permeable peptides (CPPs) targeting the PS1 or GLT-1 binding site. We used HIV TAT domain to allow for cell penetration which was assayed in neurons. First, we assessed the toxicity and penetration of CPPs by confocal microscopy. Next, to ensure the efficiency of CPPs, we monitored the modulation of GLT-1-PS1 interaction in intact neurons by fluorescence lifetime imaging microscopy. We saw significantly less interaction between PS1 and GLT-1 with both CPPs. Our study establishes a new tool to study the functional aspect of GLT-1-PS1 interaction and its relevance in normal physiology and AD models.
Topics: Animals; Humans; Mice; Alzheimer Disease; Amyloid Precursor Protein Secretases; Binding Sites; Excitatory Amino Acid Transporter 2; Fluorescence Resonance Energy Transfer; HEK293 Cells; Neurons; Presenilin-1; Protein Binding; Peptides
PubMed: 38499151
DOI: 10.1016/j.jbc.2024.107172 -
BioRxiv : the Preprint Server For... Mar 2024Whether neurodegenerative diseases linked to misfolding of the same protein share genetic risk drivers or whether different protein-aggregation pathologies in...
Whether neurodegenerative diseases linked to misfolding of the same protein share genetic risk drivers or whether different protein-aggregation pathologies in neurodegeneration are mechanistically related remains uncertain. Conventional genetic analyses are underpowered to address these questions. Through careful selection of patients based on protein aggregation phenotype (rather than clinical diagnosis) we can increase statistical power to detect associated variants in a targeted set of genes that modify proteotoxicities. Genetic modifiers of alpha-synuclein (ɑS) and beta-amyloid (Aβ) cytotoxicity in yeast are enriched in risk factors for Parkinson's disease (PD) and Alzheimer's disease (AD), respectively. Here, along with known AD/PD risk genes, we deeply sequenced exomes of 430 ɑS/Aβ modifier genes in patients across alpha-synucleinopathies (PD, Lewy body dementia and multiple system atrophy). Beyond known PD genes and , rare variants AD genes (, and ) and Aβ toxicity modifiers involved in RhoA/actin cytoskeleton regulation () were shared risk factors across synucleinopathies. Actin pathology occurred in iPSC synucleinopathy models and RhoA downregulation exacerbated ɑS pathology. Even in sporadic PD, the expression of these genes was altered across CNS cell types. Genome-wide CRISPR screens revealed the essentiality of in both human cortical and dopaminergic neurons, and mutation carriers exhibited diffuse brainstem and cortical synucleinopathy independent of AD pathology. contributes to a common-risk signal in PD GWAS and regulates ɑS expression in neurons. Our results identify convergent mechanisms across synucleinopathies, some shared with AD.
PubMed: 38496508
DOI: 10.1101/2024.03.03.583145